tunnel shading

[gbajam21] / src / gamescr.c

diff --git a/src/gamescr.c b/src/gamescr.c
index 2744d5d..5305c8b 100644 (file)
--- a/src/gamescr.c
+++ b/src/gamescr.c
@@ -13,7 +13,7 @@
 static void draw_tunnel(void);
 static void vblank(void);
 
-static int nframes, backbuf;
+static int nframes, num_vbl, backbuf;
 static uint16_t *vram[] = { (uint16_t*)VRAM_LFB_FB0_ADDR, (uint16_t*)VRAM_LFB_FB1_ADDR };
 static unsigned char *tex;
 static uint16_t bnstate;
@@ -90,10 +90,15 @@ void gamescr(void)
        }
 }
 
+#define TUN_U(x)       ((x) & 0x3f)
+#define TUN_V(x)       (((x) >> 6) & 0x3ff)
+#define TEXEL(x, y, lvl) \
+       tuncross_shade[((int)tex[((y) << 5) + (x)] << 3) + (lvl)]
+
 __attribute__((noinline, target("arm"), section(".iwram")))
 static void draw_tunnel(void)
 {
-       int i, j, tx, ty, angle, depth, zoffs, uoffs, flip, tunturn;
+       int i, j, tx, ty, u, v, angle, depth, zoffs, uoffs, flip, tunturn, shade;
        static int tunsweep;
        uint16_t pptop, ppbot;
        uint16_t *top, *bot;
@@ -107,9 +112,8 @@ static void draw_tunnel(void)
        flip = tunsweep < 0;
        tunturn = abs(tunsweep) & 0x1f;
 
-       zoffs = nframes;
-
-       uoffs = flip ? -nframes : nframes;
+       zoffs = num_vbl;
+       uoffs = (flip ? -num_vbl : num_vbl) >> 1;
 
        top = vram[backbuf];
        bot = vram[backbuf] + 159 * 240 / 2;
@@ -120,23 +124,24 @@ static void draw_tunnel(void)
                for(i=0; i<80; i++) {
                        for(j=0; j<240/2; j++) {
                                tun = *--tunptr;
-                               tun = (tun >> 16) | (tun << 16);
 
-                               angle = tun & 0xff;
-                               depth = (tun >> 8) & 0xff;
-                               tx = ~((angle >> 1) - uoffs) & 0x1f;
+                               angle = TUN_U(tun >> 16);
+                               depth = TUN_V(tun >> 16);
+                               shade = depth >> 7;
+                               tx = ~(angle - uoffs) & 0x1f;
                                ty = ((depth >> 1) + zoffs) & 0x1f;
-                               pptop = tex[(ty << 5) + tx];
-                               tx = ((angle >> 1) + uoffs) & 0x1f;
-                               ppbot = tex[(ty << 5) + tx];
-
-                               angle = (tun >> 16) & 0xff;
-                               depth = (tun >> 24) & 0xff;
-                               tx = ~((angle >> 1) - uoffs) & 0x1f;
+                               pptop = TEXEL(tx, ty, shade);
+                               tx = (angle + uoffs) & 0x1f;
+                               ppbot = TEXEL(tx, ty, shade);
+
+                               angle = TUN_U(tun);
+                               depth = TUN_V(tun);
+                               shade = depth >> 7;
+                               tx = ~(angle - uoffs) & 0x1f;
                                ty = ((depth >> 1) + zoffs) & 0x1f;
-                               pptop |= (uint16_t)tex[(ty << 5) + tx] << 8;
-                               tx = ((angle >> 1) + uoffs) & 0x1f;
-                               ppbot |= (uint16_t)tex[(ty << 5) + tx] << 8;
+                               pptop |= (uint16_t)TEXEL(tx, ty, shade) << 8;
+                               tx = (angle + uoffs) & 0x1f;
+                               ppbot |= (uint16_t)TEXEL(tx, ty, shade) << 8;
 
                                *top++ = pptop;
                                *bot++ = ppbot;
@@ -149,21 +154,23 @@ static void draw_tunnel(void)
                        for(j=0; j<240/2; j++) {
                                tun = *tunptr++;
 
-                               angle = tun & 0xff;
-                               depth = (tun >> 8) & 0xff;
-                               tx = ((angle >> 1) - uoffs) & 0x1f;
+                               angle = TUN_U(tun);
+                               depth = TUN_V(tun);
+                               shade = depth >> 7;
+                               tx = (angle - uoffs) & 0x1f;
                                ty = ((depth >> 1) + zoffs) & 0x1f;
-                               pptop = tex[(ty << 5) + tx];
-                               tx = ~((angle >> 1) + uoffs) & 0x1f;
-                               ppbot = tex[(ty << 5) + tx];
-
-                               angle = (tun >> 16) & 0xff;
-                               depth = (tun >> 24) & 0xff;
-                               tx = ((angle >> 1) - uoffs) & 0x1f;
+                               pptop = TEXEL(tx, ty, shade);
+                               tx = ~(angle + uoffs) & 0x1f;
+                               ppbot = TEXEL(tx, ty, shade);
+
+                               angle = TUN_U(tun >> 16);
+                               depth = TUN_V(tun >> 16);
+                               shade = depth >> 7;
+                               tx = (angle - uoffs) & 0x1f;
                                ty = ((depth >> 1) + zoffs) & 0x1f;
-                               pptop |= (uint16_t)tex[(ty << 5) + tx] << 8;
-                               tx = ~((angle >> 1) + uoffs) & 0x1f;
-                               ppbot |= (uint16_t)tex[(ty << 5) + tx] << 8;
+                               pptop |= (uint16_t)TEXEL(tx, ty, shade) << 8;
+                               tx = ~(angle + uoffs) & 0x1f;
+                               ppbot |= (uint16_t)TEXEL(tx, ty, shade) << 8;
 
                                *top++ = pptop;
                                *bot++ = ppbot;
@@ -180,6 +187,8 @@ static void vblank(void)
        int16_t mat[4];
        static short gate_speed;
 
+       num_vbl++;
+
        bnstate = ~REG_KEYINPUT;
        if(bnstate & BN_DPAD) {
                if(gate_speed < 5) {